Seismic Resilience Evaluation Of Reinforced Concrete Frame Accounting For The Influence Of Mainshock-aftershock Sequence

Aftershocks often occur after an earthquake.The structures in civil engineering has a certain degree of damage after the main shock.If aftershocks happened,the damage could be aggravated or even collapse.Therefore,it is necessary to analyze the influence of the mainshock-aftershock on the seismic capacity and resilience of the structure.Resilience of an engineering structure refers to the ability of the structure to restore its original state through artificial repair or self-repair after encountering an earthquake.Resilience can measure the ability of functional recovery and it has become an important evaluation index for the disaster prevention capabilities of engineering structures,communities,and lifeline systems.This paper takes a reinforced concrete frame structure as the research object.On the basis of vulnerability analysis,the seismic resilience of the reinforced concrete frame is calculated according to the trigonometric recovery model.First,based on the contents of our country Building Seismic Design Code and the Structure Seismic Design Code,the analysis method of the normalized economic loss of the building structure and the resilience index under a single earthquake has been improved.Then,considering the occurrence of aftershocks,the calculation method of the resilience index of the structure under the action of the mainshock-aftershock is demonstrated,and the random factors affecting the resilience of the mainshock-aftershock are then analyzed.Finally,taking an8-story concrete frame structure as the testing engineering background,based on the main shock vulnerability curve and the aftershock damage increment analysis,the mainshock-aftershock resilience of the structure under the three earthquake intensity levels of frequent,fortified and rare earthquakes is calculated,and the influence of the number of simulations is analyzed.According to the different time intervals of the mainshock-aftershocks,there are three scenarios for consideration.Based on the trigonometric recovery model,the seismic resilience under different intensities is compared and analyzed.The comparison shows that with the increase of ground motion intensity,the earthquake loss and recovery time of the structure gradually increase,and the resilience of the structure decreases.If the aftershock occurs before the completion of the structural repair after the main shock,the shorter the mainshock-aftershock interval,the smaller the resilience is.This study can provide a theoretical reference for the seismic performance evaluation of reinforced concrete frame structures under mainshock-aftershocks.